The invention described herein relates to timing devices for electrical power circuits like lighting and appliance circuits in residences. In recent years a large demand for automatic and/or remote control of residential lighting has developed as a result of the increased crime rate involving home invasions. Automatically timed control of lighting has become widely accepted as a significant deterrent for prevention of home invasion. Also, the remote operation of lights, either automatically, from an intrusion alarm system, or from a remote location such as a bedside unit, is a desirable feature of a home protection system.
Automatic light timers commonly available today are motor driven mechanically activated switches. The least expensive type provides a single "on" time selection and a single "off" time selection for each 24 hour period. Some mechanical timers provide for the selection of one hour "on" or "off" intervals that can be arranged in any pattern. The pattern is repeated every 24 hours. The most popular timer type is self contained, with a two-prong plug integral with a housing therefore for directly plugging into the usual houshold electrical outlet. The housing also has an integral socket for plugging in the lamp or appliance to be controlled. Another timer type has a power cord and is designed for setting on the floor or table top. Some manufacturers offer timers for permanent wall mounted installation to control lighting fixtures. To further enhance the usefulness of automatic light timers as a deterrent against home invasions, some timers have a feature that alters the actual "on" time from day to day so that a more probable "lived in" pattern results.
Mechanical motor driven timers have achieved great popularity because of their low cost. However, because of the limitations of mechanical systems, mechanical timers presently in use suffer from a number of disadvantages. Thus, mechanical timers tend to be unreliable and noisy (especially after some period of use), forcing many owners to abandon their use in quiet areas such as studies and bedrooms. Mechanical timers are also large and bulky and therefore have not lent themselves widely to convenient table-top use with "decorator" type styling. The size and bulk of mechanical timers precludes their installation into a flush device electrical box, such as commonly houses wall switches for the control of outdoor or ceiling lighting fixtures.
Inexpensive mechanical timers have "MANUAL/AUTOMATIC" settings on a switch selector. When the timer is in the "AUTOMATIC" mode usually the light cannot be turned on or off without taking the timer out of the "AUTOMATIC" mode. Thus if it is desired to change the light from its present automatically programmed state to the opposite state (ON to OFF or OFF to ON) the user must remember to return to "AUTOMATIC" before leaving the room if he wants programmed control to continue. However, some mechanical timers heretofore developed have an automatic override feature where the automatic control returns to operation automatically when the manual setting and automatic setting subsequently correspond.
It is, accordingly, one of the objects of the invention to provide a timer, which has its most important but not its only application to automatically energize and de-energize home lighting, entertainment equipment or appliance circuits, and wherein the timer is capable of providing a number of "on" and "off" intervals over a twenty-four hour period by electrical control circuitry which may be made in the form of integrated circuits, so that the resulting timer operates quitely and can be made in a very compact and attractive form. A related object of the invention is to provide a timer as just described where it can be incorporated in the small space which usually accommodates a conventional wall switch or in a small enclosure readily plugable into an electric outlet, or can appear as an unobtrusive and attractive component or device settable on a table and connected to an electric outlet through a power cord.
Another object of the invention is to provide a timer as described wherein the control circuitry of the timer is such that when the timer is automatically controlling the energization of the power circuit involved, automatic control thereover can be temporarily overidden by operation of the manually operable switch means which controls the energization of the power circuit when the timer is not in use and which subsequently resumes control when the automatic control setting corresponds to the manual setting.
A still further object of the invention is to provide a timer meeting any one or more of the previously stated objectives of the invention and, furthermore, includes manual controls which enable the timer to be programmed for a wide variety of power "on" or power "off" intervals in such an easy manner that even a young child can program the timer.
Another object of the invention is to provide a timer meeting any one or more of the previously described objectives and wherein the timer memorizes the normal manner in which a given lighting power circuit is energized and de-energized during a normal twenty-four hour period, so that the timer system is more effective in making it appear to potential burglars that the home involved is occupied.
Still another object of the invention is to provide a timer satisfying any one or more, and preferably all of the previously states objectives, and which can be made to sell for a price, in some cases, no more than existing timers not having the advantages of the invention, and in some cases only modestly more than prior timer devices where the timer of the invention includes features not found in the lower priced version thereof.